Molecular outflows and H2O masers: What type of connection?

Felli, M.; Palagi, F.; Tofani, G.

doi:10.1007/3-540-56343-1_232

Cited by 61 publications

(86 citation statements)

References 1 publication

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“…G.1, while part of the external layers of the globule can be seen at the edge of the SPIRE maps in the same figure. The same globule was observed at radio wavelengths by Felli et al (1992), who propose a similar distance of 230 pc based on a kinematic method. Looking the IRAS 100 µm data of this region suggests that our cloud is more likely associated with the molecular complex than with LDN 100.…”

Section: D5 G308+938supporting

confidence: 69%

Galactic cold cores

Montillaud

Juvela

Rivera-Ingraham

et al. 2015

A&A

160

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Context. For the project Galactic cold cores, Herschel photometric observations were carried out as a follow-up of cold regions of interstellar clouds previously identified with the Planck satellite. The aim of the project is to derive the physical properties of the population of cold sources and to study its connection to ongoing and future star formation. Aims. We build a catalogue of cold sources within the clouds in 116 fields observed with the Herschel PACS and SPIRE instruments. We wish to determine the general physical characteristics of the cold sources and to examine the correlations with their host cloud properties. Methods. From Herschel data, we computed colour temperature and column density maps of the fields. We estimated the distance to the target clouds and provide both uncertainties and reliability flags for the distances. The getsources multiwavelength source extraction algorithm was employed to build a catalogue of several thousand cold sources. Mid-infrared data were used, along with colour and position criteria, to separate starless and protostellar sources. We also propose another classification method based on submillimetre temperature profiles. We analysed the statistical distributions of the physical properties of the source samples. Results. We provide a catalogue of ∼4000 cold sources within or near star forming clouds, most of which are located either in nearby molecular complexes ( 1 kpc) or in star forming regions of the nearby galactic arms (∼2 kpc). About 70% of the sources have a size compatible with an individual core, and 35% of those sources are likely to be gravitationally bound. Significant statistical differences in physical properties are found between starless and protostellar sources, in column density versus dust temperature, mass versus size, and mass versus dust temperature diagrams. The core mass functions are very similar to those previously reported for other regions. On statistical grounds we find that gravitationally bound sources have higher background column densities (median N bg (H 2 ) ∼ 5 × 10 21 cm −2 ) than unbound sources (median N bg (H 2 ) ∼ 3 × 10 21 cm −2 ). These values of N bg (H 2 ) are higher for higher dust temperatures of the external layers of the parent cloud. However, only in a few cases do we find clear N bg (H 2 ) thresholds for the presence of cores. The dust temperatures of cloud external layers show clear variations with galactic location, as may the source temperatures. Conclusions. Our data support a more complex view of star formation than in the simple idea of a column density threshold. They show a clear influence of the surrounding UV-visible radiation on how cores distribute in their host clouds with possible variations on the Galactic scale.

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Section: D5 G308+938supporting

confidence: 69%

Galactic cold cores

Montillaud

Juvela

Rivera-Ingraham

et al. 2015

A&A

160

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“…In the case of BRC 30 and 36 the emission displayed in Fig. 1 represents a first time detection, while the maser in BRC 38 was first found by Felli et al (1992). We note that 5 BRCs were also included in Furuya et al (2003) survey towards low-mass YSOs (BRC 16,18,38,39,44).…”

Section: Resultsmentioning

confidence: 74%

H$_{\mathsf{2}}$O maser emission from bright rimmed clouds in the northern hemisphere

Valdettaro¹,

Chapman²,

Lovell

et al. 2005

A&A

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We report the results of a multi-epoch survey of water maser observations at 22.2 GHz with the Medicina radiotelescope from 44 bright rimmed clouds (BRCs) of the northern hemisphere identified by Sugitani et al. (1989, ApJ, 342, L87) as potential sites of star formation. The data span 16 years of observations and allow to draw conclusions about the maser detection rate in this class of objects. In spite of the relatively high far-infrared luminosities of the embedded sources (L FIR > ∼ 10 2 L ), H 2 O maser emission was detected towards three globules only. Since the occurrence of water masers is higher towards bright IRAS sources, the lack of frequent H 2 O maser emission is somewhat surprising if the suggestion of induced intermediate-and high-mass star formation within these globules is correct. The maser properties of two BRCs are characteristic of exciting sources of low-mass, while the last one (BRC 38) is consistent with an intermediate-mass object. We argue that most BRCs host young stellar objects of low-luminosity, likely in an evolutionary phase later than the protostellar Class 0 sources, and that a significant contribution to the observd IRAS luminosity comes from warm dust heated by the radiation from the bright rim.

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“…As a result, weaker maser emission may be generated in W3 IRS 5. Felli, Palagi, & Tofani (1992) empirically found that the luminosity of a water maser source increases with the kinetic energy of the outÑow. They did not estimate the kinetic energy of the W49N Ñow.…”

Section: T Urbulent Motions Clustering and L Uminosity Of Maser Spomentioning

confidence: 99%

Microstructure of Water Masers in W3 IRS 5

Imai

Deguchi

Sasao

2002

ApJ

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We report sub-milliarcsecond structures of water maser features in W3 IRS 5 observed with the Very Long Baseline Array (VLBA) at 22.2 GHz. A cluster of maser spots (emission spots in individual velocity channels) within a maser feature exhibits a simple velocity gradient but a complicated spatial alignment. Two-point spatial correlation functions for the spots can be Ðtted by power laws with an index of about 2 in both of the two ranges of 0.04È0.4 and 1È300 AU. This fact indicates a similar clustering of spots in the two very di †erent ranges. The Doppler-velocity di †erence of the spots as a function of spot separation demonstrates a Kolmogorov-type turbulence in the range of 0.04È300 AU. Similar power laws in these functions have been reported for the W49N water masers. A unique di †erence of the W3 IRS 5 from the W49N masers is that on a scale above 1 AU, the Doppler-velocity di †erence of the spots in W3 IRS 5 (¹5 km s~1) is much smaller than that in W49N (¹150 km s~1). Very likely, this di †erence between the two sources arises because of di †erent outÑow velocities. Subject headings : ISM : individual (W3 IRS 5) È ISM : jets and outÑows È masers È methods : statistical

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Molecular outflows and H2O masers: What type of connection?

Cited by 61 publications

References 1 publication

Galactic cold cores

Galactic cold cores

H$_{\mathsf{2}}$O maser emission from bright rimmed clouds in the northern hemisphere

Microstructure of Water Masers in W3 IRS 5

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